This invention relates generally to nanoparticles and more particularly to the use of nanoscale sterols and sterol esters in cosmetics.
Prior Art
Sterols and sterol esters are important raw materials both for cosmetics and pharmaceutical products and for the food industry. For example, it is known that sterols, especially vegetable representatives ("phytosterols"), are incorporated in the basal membrane of the skin and pass to the skin surface through the differentiation of the skin cells. This would explain the caring and protecting effect of phytosterols in skin cosmetics. The topical application of sterols also leads to an increased skin moisture level and to an increased lipid content. This improves the desquamation behavior of the skin and reduces any erythemas present. According to more recent studies, sterols (again preferably phytosterols) act on the arachidonic acid cascade by reducing the leucotriene level. However, high concentrations of leucotrienes in the skin are always accompanied by inflammatory reactions, as is the case for example with atopical dermatitis, psoriasis and UV erythemas. Accordingly, sterols also have an inflammation-inhibiting effect. In the field of skin care, sterol-containing preparations produce an improvement in combability and tear strength, especially in the case of bleached hair. Overviews on the properties of sterols and sterol esters in cosmetics have been published, for example, by R. Wachter in Parf. Kosm. 75, 755 (1994) and in Cosm. Toil. 110, 72 (1995). Reference is also made to German patent application DE-A1 19522822 (Henkel) which proposes mixtures of sterols and fatty alcohols for cosmetic applications. The antimicrobial effect of sterols and sterol derivatives is known, for example, from European patent application EP-A1 0 838 155 (Beiersdorf).
The effect of sterols and sterol esters is always associated with the rate at which the compounds are incorporated or absorbed. So far as the substances available at present are concerned, there is considerable potential for improvement in this regard. Accordingly, the problem addressed by the present invention was to accelerate the absorption of topically applied sterols and sterol esters by presenting them in new forms.